Psoriasis, also called as “lepra alphos”, is a common chronic, recrudescent, inflammatory skin disease, characterized in that multiple layers of silvery white, dry scales occur repeatedly on erythema. In the Chinese traditional medicine it is called “Baibi”. It is also called “Songpi Xian” in ancient medical books. In the western medicine, it is called psoriasis. Psoriasis usually occurs in scalp, extensor aspect of arms and legs, and on the back. Psoriasis relapses or becomes worse in spring and winter while relieves in summer and autumn. Psoriasis is one of the ten recurring illnesses as listed by WHO, having a morbidity of about 2-3% in Europe and USA (Schoen and Boehncke, N Engl J Med, 2005). In China, according to incomplete statistics, the incidence of psoriasis is about 0.5%, and there are about 7 million of patients suffering from psoriasis. Psoriasis mainly occurs in young adults of 25 to 45 years old, accounting for about 81%. Recently, children's incidence is increasing. Psoriasis is difficult to be cured and readily occurs repeatedly, thus it not only causes physical pain but also causes a huge psychological burden for the patients and seriously affect their life quality. As a result, psoriasis is one of the important research subjects in the field of skin disorders in the world.
Treatment of psoriasis is expensive in the world, especially in the case of using the expensive biological drugs. Therefore, it is an urgent need to develop drugs with low price and good safety for treating psoriasis. The research results made by the present inventors show that the nucleic acid transcription factor, NF-kappa B, is over activated in epidermis and dermis of the patients with psoriasis as compared to the skin of a normal person, which leads to a great release of the inflammatory factors, such as TNF-alpha, IL-17 and IL-23 etc. Excessive amounts of inflammatory factors, such as TNF-alpha, IL-17 and IL-23, induce human psoriasis (Wang et al., J Immunol, 2009).
One of the drugs currently used for treating psoriasis approved by FDA, etanercept, is a bio-agent, which is an inhibitor of tumor necrosis factor. Etanercept is a humanized antibody for blocking the receptor of the tumor necrosis factor. Since the tumor necrosis factor is essential in the normal immune response in organism, the humanized antibody non-selectively blocks the tumor necrosis factor, resulting in side effects after administration or even easy to recurrence after stopping administration. Moreover, since it is an antibody, it has a high production cost and thus it is expensive, the ordinary patients are difficult to afford expenses for drugs. Additionally, ustekinumab, which is a monoclonal antibody against IL-23, clinically exhibits a very well treatment effect on psoriasis. But it has a high production cost and an expensive price.
Acetyl-11-keto-β-boswellic acid (AKBA) is one of the important components of the colloidal resin, frankincense, from Boswellia carterii Birdw. Concentration and purification of AKBA from natural mastic tree extract has been described in WO 03/0746, US 20030199581 and WO 03/077860. Product with high purity may be obtained via chromatography separation and re-crystallization. Frankincense extract has been used as an anti-inflammatory agent in the traditional medicine for treating patients suffering from, such as arthritis and ulcerative colitis. Additionally, boswellic acid is also noticeable due to their anti-proliferative property. Boswellic acid can inhibit several leukaemia cell lines, growth of melanoma and death of cells in vitro. Study on boswellic acid shows that acetyl-11-keto-β-boswellic acid exhibits the most obvious 5-LOX inhibitory activity (Sailer et al., British J Pharmacology, 1996). AKBA has a structure as set forth below:

The present inventors have been working on the pathogenesis and treatment of psoriasis for many years. Molecular immunological mechanism of AKBA in treating psoriasis has been clarified by using a mouse model for psoriasis by the present inventors. The research results were published on October 2009 in The Journal of Immunology (Wang et al., J Immunol, 2009). The innovative research results have been highly concerned by the international counterparts after its publication and were reported by Nature Reviews Rheumatology, one of the international authoritative magazines, as a research highlight.
Generally speaking, the existing drugs for treating psoriasis have a high production cost and poor targeting property. Acetyl-11-keto-β-boswellic acid can be used to treat psoriasis but it still needs to be further modified to greatly improve the treatment effect.